题：

• flag1, flag3& flag5AFAIK 在编译时本身解析变量值，因此它必须给出错误。

• flag2, flag4& Boolean.FALSE: 为什么我们没有得到编译时错误？

• 找到 1 个参考，但不完全相同。

  为什么在显式布尔测试上有死代码警告，而在隐式测试上没有

代码：

public static void main(final String[] args) {
    final boolean flag1 = false;

    final Boolean flag2 = Boolean.parseBoolean("false");

    final boolean flag3 = !true;

    final Boolean flag4 = 100 == 20;

    final boolean flag5 = 10 >= 20;

    while (flag1) { System.out.println("this is unreachable code with compile error"); break;  }

    while (flag5) { System.out.println("this is unreachable code with compile error"); break;  }        

    while (flag3) { System.out.println("this is unreachable code with compile error"); break;  }
    
    while (flag2) { System.out.println("this is uncreachable code without compile error"); break;  }

    while (flag4) { System.out.println("this is uncreachable code without compile error"); break;  }

    while (Boolean.FALSE) { System.out.println("this is uncreachable code without compile error"); break;  }

}

输出：

.comlogicst4_19_Tst.java:15: error: unreachable statement
        while (flag1) { System.out.println("this is unreachable code with compile error"); break;  }
                      ^
.comlogicst4_19_Tst.java:17: error: unreachable statement
        while (flag5) { System.out.println("this is unreachable code with compile error"); break;  }        
                      ^
.comlogicst4_19_Tst.java:19: error: unreachable statement
        while (flag3) { System.out.println("this is unreachable code with compile error"); break;  }        
                      ^
3 errors

java version "1.8.0_261"
Java(TM) SE Runtime Environment (build 1.8.0_261-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.261-b12, mixed mode)

回答